GM Papaya with Improved Resistance to Mites

Researchers at the Hawaii Agriculture Research Center and the USDA-ARS Pacific Basin Agricultural Research Center have reported that a transgenic papaya with a snowdrop lectin (Galanthus nivalis agglutin [GNA]) gene exhibited improved resistance to carmine spider mites (Tetranychus cinnabarinus). Lectins are naturally occurring proteins that typically bind to carbohydrates and are found in plants, animals, bacteria and fungi.

Heather McCafferty and colleagues transformed the commercial papaya cultivar Kapoho which is highly susceptible to mites. The group used the biolistic transformation method to introduce a plasmid containing the GNA DNA to embryogenic calli. Laboratory assay indicated the total reproductive capacity of mites feeding on leaves of the transgenic lines was significantly different and about three times less in the transformed lines. The researchers noted that mites were also found to spend less time feeding on leaves of the transgenics and this mite feeding behavior may be as significant as the insecticidal activity of the protein.

McCafferty and colleagues plan to further conduct experiments to test the resistance of the transgenic papaya plants to other pathogens and determine the impact of GNA-expressing papayas on the flora and fauna found in Hawaii.

The paper is available at the Plant Science journal website at http://dx.doi.org/10.1016/j.plantsci.2008.05.007.